IRCTC ticket cancel charges may be different depending on your ticket status.But in a small sentence I can say the more closed departure time you cancel,your cancel charge would be getting more high.Therefore try to cancel ticket atleast before 4 or 5 days to reduce cancellation charge.
However see the below table to get the detail cancellation charges for only confirmed tickets : This table charge indicates, if the ticket is presented for cancellation more than forty eight hours in advance of the scheduled departure of the train.
 Class of your ticket |  Cancellation charges per passenger |
 AC First/Executive Class |  Rs. 120 |
 First Class/AC 2 Tier |  Rs. 100 |
 AC Chair Car/AC 3Tier/AC 3 Economy |  Rs. 90 |
 Sleeper Class |  Rs. 60 |
Second Class | Â Rs. 30 |
If the ticket is presented for cancellation between forty eight hours and upto six before the scheduled departure of the train
| 25%(twenty five) percent of fare subject the minimum of the cancellation charge hours |
If the ticket is presented for cancellation within six hours before the scheduled departure of the train and upto two hours after the actual departure of the train irrespective of distance | 50%(Fifty) percent of fare subject to a minimum of the cancellation charge would be applied |
Note: No refund shall be granted on reserved ticket if its surrendered for cancellation
after two hours of the actual departure of the train.